1. Field of the Invention
The present invention relates to the field of gas exchange devices and more particularly, to a device designed to inject inert gas into the interior of a tire and displace the existing tire air while controlling the exiting gases to allow monitoring of relative humidity.
2. Description of the Related Art
The proper pressure maintenance of a pressurizable article depends upon the particular use and application of a pressurizable article. Typically, the primary needs relating to pressurizable articles is to simply maintain a desired pressure, as gas pressure inside an article will typically effect the operation and function of the article, whether it be a vehicle tire, an air mattress or life preserver. Depending upon the material used and quality of "air tightness", a pressurizable article will typically lose compression over time. This can is usually corrected by simply re-inflating the article. Under special circumstances, however, a pressurizable article may be subject to variable temperature conditions. If the temperature fluctuations are substantial, the air pressure inside the article may fluctuate dramatically without the introduction or release of any air into or out of the pressurizable article. Depending upon the particular application of the pressurizable article, its performance and use may be adversely effected by such a dramatic increase or decrease in pressure.
An example of a pressurizable article whose performance may be acutely affected by fluctuations in temperature is a vehicle tire. In particular, the added heat created from friction of a tire used on a high speed automobile may increase air temperature inside the tire by more than 240 degrees Fahrenheit. Under ideal gas (or inert gas) conditions the increase in air pressure is functionally related to the increase in temperature and may even be predicted. Under such "ideal" conditions, tire pressure increases are not likely to fluctuate dramatically, but instead would simply be incremental in accordance with the ideal gas law. However, the presence of an impurity such as moisture or water inside a tire can cause a detrimental alteration of the internal tire pressure.
Under certain auto racing conditions, the vehicle tires may reach very high temperatures. Unless the tires are completely vacated of impure air, even the smallest amount of moisture may be present in the tire originally from the manufacture or moisture may enter the tire through inflation with ambient air containing a significant relative humidity levels. The effect of water inside a tire may have an extreme effect upon tire pressure after an increase in temperature. This is particularly the case if the desired tire pressure is initially established when water that is present in the tire may in a condensed or liquid form and, after being exposed to a significant increase in temperature, the condensed liquid changes to a gaseous form thereby dramatically increasing the pressure inside the tire. Auto racing performance depends upon numerous variables including the ability to control such variables. Dramatic fluctuations in tire pressure will adversely affect auto car handling and will result in a competitive disadvantage.
Most existing air inflation and deflation control devices for pressurizable articles are designed to make it easier to control the existing pressure within a pressurizable article. Examples of such inventions and devices include U.S. Pat. No. 5,297,576 to Weinheimer which is described as an oral inflation and relief tube. This device is designed to act as both an inflation and relief valve for inflatable objects. The inflation relief tube is equipped with a mounting flange that can be sealed through the wall of a bladder of the inflation article. The pressurizable article may be easily inflated or deflated by simply manipulating the proper end of the oral inflation and relief tube. The Weinheimer invention, however, is not designed to displace or exchange existing air inside the pressurizable article or reduce humidity levels within the pressurizable article.
Another example of a pressure control device is described in U.S. Pat. No. 5,181,977 to Gneiding et al. which is a tire inflation valve having an over-pressure and flow control. This device is intended to replace and existing valve mount. The new valve regulates over pressuring the tire by having an internal valve disc lift when the predetermined pressure is reached thereby venting the fill gas. Although this device is well suited to control over pressure problems within a tire, if the tire cools in temperature, there may be a significant decrease in pressure, particularly if the tire gas has a high relative humidity. Such an under-inflated condition would be unacceptable for certain operations.
An example of a device designed to filter out moisture from a compressed gas prior to injection into an inflatable article or pneumatic hose is U.S. Pat. No. 5,522,910 to Fogal, Sr. described as an end-line compressed air moisture filter. The device contains an internal filter element designed to remove the moisture from the compressed air as the air passes through the valve stem.
As is evidenced by the cited prior art, there exist numerous devices designed to control over pressure of pressurizable articles or even the moisture content of injected air; however, none of these devices are designed to displace the existing air and moisture in a pressurizable article while allowing for the monitoring of relative humidity levels of the exhausted gases. The present invention is specially designed to inject inert, moisturefree gas into a pressurizable article to replace the existing air inside the pressurizable article. During the air replacement process the exhausted air may be monitored for moisture content for the purpose of ensuring that the pressurizable article contains a very low relative humidity level. For best result, the injected, inert gas is heated prior to injection into the tire so that water condensation within the tire interior will more easily be volatilized and evacuated from the interior of the tire. The present invention is ideally suited for use in auto racing conditions where auto tire pressure stability can be crucial for maximum performance.